FI112618B - chipping blade - Google Patents

Description

112618

chipping blade

Background of the Invention

The invention relates to a chipping blade for use in, for example, wood chipping, wherein the blade has a sharply angled face and a chest surface, whereby a chip or the like which is detachable from the material to be chipped is formed on the side of the face.

The invention is particularly applicable to a blade used in wood chipping for cutting wood or other material so that the cutting force is applied to the blade tip and forms a wear force.

10 In the paper and pulp industry, wood chips are commonly used to produce wood chips, in which the wood is chipped with blades approximately radially attached to the disc. As the disc rotates, the blades strike the chopper, which on its opposite side penetrates into the counter-blade at the end of the chop feed hopper. A disc harvester is described, for example, in Fl patent 1579799.

Blades are the fastest wearing parts in disc searches. The wear of the blade, i.e. the rounding of its tip, reduces the quality of the chips, producing more unwanted fine particles in the pulping process, and reducing the ability of the chip to absorb the wood. Usually, worn blades are sharpened and then re-used. There are also so-called. disposable blades which are ·; ·· After one use. In any case, the life of the blades should be: * ·, · as long as possible, as the time it takes to replace the blades will reduce the search usage. : degrees.

. ·. | F1 95785 discloses a method of blade durability! 25 to increase compression by cold pressing at the tip of the blade.

It is stated in the publication that the compression tension improves the wear resistance of the blade mouth and also the wear resistance. However, the functionality of the invention is limited by the fact that, in the worst case scenario, the number of load change times is less than 500,000, which is quite low for hardened tool steels with very good surface roughness. In addition, heat treatment. ·; ·. post-cold cold working will, in the worst case, change the blade. van residual austenite by machining to unleashed martensite, which has a very low toughness compared to the liberated martensite and exposes: ': to the steel edge damage.

2 112618

Summary of the Invention

The object of the invention is to improve the chipping blade so that the above problems can be solved. This object is achieved by a chipping blade according to the invention, characterized in that the surface is coated with a material having a hardness of at least 700 HV.

By coating only the blade face, a self-sharpening effect is achieved, i.e. the blade face, i.e. the release face, wears out faster than the face and thus reduces the blade angle at the very tip of the blade, which means less unwanted fines. At the same time, the total blade angle is reduced by 10 compared to the uncoated blade.

Coating is useful throughout the life of the blade because after each re-etching the blade has a non-damaged coating edge.

The invention can equally be applied to drum cutters commonly used in saws, for example. In drum trimming, the trees are chipped with 15 blades attached to the periphery of the drum approximately parallel to the axis of the drum.

List of figures

The invention will now be described in more detail with reference to the accompanying drawing in which

Figure 1 illustrates the generation of chips using the chip 20 blade subject to the invention; '·': Figure 2 shows a blade according to the invention; Figures 3 to 5 illustrate the principle of self-sharpening.

DETAILED DESCRIPTION OF THE INVENTION; Referring to Figure 1, the wood 1 to be chipped therein is disposed in an oblique position in the feed trough 2 against this feed trough 2 and the stop blade 3 'at its end. The chip 1 detaching the wood 1 from the wood 1 is denoted by the reference numeral 5. The chip blade 5 is each mounted on a blade disc wear plate 6, which in turn is secured to a blade disc not shown. The direction of rotation of the blades 5 and the blade disc naturally follows the arrows A.

30 The surface of the blade 5 on the side of the resulting chip 4 is generally referred to as the surface 7 and the second surface associated with this acute angle as the forehead 8. In the chopping process, the area perpendicular to plane C and 7, respectively, cuts the wood at a sharp angle) G. Correspondingly, the area between the tangent plane D of the blade passing through the tip of the blade 5 and the face 8 of the blade 5 can be called the face area F. The angle α between plane D and the face 8 the angle β and the angle γ between the thorax 7 and the plane C all influence the formation of the chip 4 (chip length, forces required for chip removal, etc.) and the wear of the blade.

By coating only the surface 7 with a material 9 having a higher wear resistance and a lower friction coefficient than the blade base material 10, the self-sharpening of the blade 5 according to Figure 5 is achieved, whereby the end surface 8 'And thus keep the blade 5 sharp despite wear-10. Sharpening (here, flattening of the face 8) is significantly less than with a conventional blade, whereby the wear is the rounding of the blade tip of Figure 4, starting from the new sharp blade of Figure 3.

The coating has a micro- or macro-hardness higher than the base macro-hardness of 15 (58-60 HRC), i.e., at least 700 HV. The coefficient of friction of the coating against the wood is correspondingly lower and at least 0.6.

The coating 9 has a thickness of less than 0.1 mm. Preferred coatings are titanium nitride, chromium nitride and chromium carbide coatings based on diffusion-based PVD and CVD coating methods. The electrolytically hardened chromium plating 20 is also suitable for the application.

The foregoing description of the invention is merely intended to illustrate the basic idea of the invention. However, a person skilled in the art can implement the details of the invention in many ways within the scope of the appended claims.

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Claims (4)

1. Chipping bite to be used, for example, in chopping trees (1), which bite (5) has an end surface (8) and a chipping surface (7) which adjoin each other at an acute angle, whereby spans or the like (4) which are detached from the material to be chipped is formed on the side of the tile surface, characterized in that the tile surface (7) is coated with a material (9) whose hardness is at least 700 HV. Chipping bite according to claim 1, characterized in that the thickness of the coating (9) is below 0.1 mm. Chipping bite according to claim 1 or 2, characterized in that the coating (9) is electrolytically produced. 4. Chipping bite according to claim 1 or 2, characterized in that the coating (9) is made by a method based on diffusion. J I